Does blender support what I could best describe as "Occlusion Planes"?
For this I would use a render layer with a mask layer set up.

In the scene I have a plane that will act as a mask on layer 2 and the switch object to be masked on layer 1. When both layers are enabled it looks like this:

Solid View:



Wire view, shows some of the switch object is below the mask object:



In the 'Render Layers' tab of the 'Properties' area I have chosen the first layer to be the layer to render and the second layer to be the mask layer:



Which results in:



This works fine for the internal renderer but for Cycles one additional option is necessary in the 'Render' tab in the 'Properties' area: